NASA has received 12 mission proposals for their New Frontiers program, which will select a spacecraft to send to a new target in the solar system with a planned launch in the mid-2020s. Of the 12 proposals, one or more will be selected for Phase A studies in November, and one mission will be chosen in early 2019 to proceed with development with a budget around $1 billion. Launch is expected sometime around 2024.

Saturn's sixth-largest moon Enceladus, with a subsurface ocean and geysers that spew water ice out into space.

NASA/JPL-Caltech/Space Science Institute

Most Popular

Although NASA does not reveal specifics of any mission proposal, the agency does have a list of "mission themes" that the proposals should focus on. This list suggests a mission to Jupiter's moon Io to study the volcanism there might be one of the proposals, as well as a mission to land on Venus. However, this is simply speculation from the list of "mission themes," which are as follows:

Comet Surface Sample Return

Lunar South Pole-Aitken Basin Sample Return

Ocean Worlds (Titan and/or Enceladus)

Saturn Probe

Trojan Tour and Rendezvous

Venus In Situ Explorer

One of the most intriguing "mission themes" is a lander to sample the South Pole-Aitken (SPA) basin of our own moon. This massive impact crater on the far side of the moon is one of the largest in the entire solar system, stretching about 1,600 miles in diameter. It is also thought to be the oldest impact crater on the moon, at least 3.9 billion years old and possibly older.

Concept of a lunar lander to sample the South Pole–Aitken basin.

NASA

Advertisement - Continue Reading Below

A sample from the SPA basin has never been obtained, and many planetary scientists are extremely eager to get their hands on some of this material because astrobiologists believe that life likely formed on Earth around the same time the SPA crater was created. Craters on Earth that are as old as the SPA basin have all been eroded away or buried under rock and water, but a sample from this lunar crater could act as a substitute for a terrestrial one. Analyzing the composition of the SPA could potentially answer one of planetary science's biggest questions—did life spark from material on Earth that stewed in the right conditions for long enough, or was it brought here by an impacting asteroid?

Enhanced-color image of Pluto taken by the New Horizons spacecraft on July 14, 2015.

NASA/JHUAPL/SwRI

The next launch of an exciting interplanetary spacecraft from NASA will be the Europa Clipper, designed to visit Jupiter's moon Europa, possibly land, and study the icy moon for signs of life. Europa Clipper is slated to launch around 2022, and the craft will be operated jointly by Johns Hopkins University's Applied Physics Laboratory (APL) and the Jet Propulsion Laboratory (JPL).

Spilker also mentioned talk within NASA about a mission like Cassini to Uranus or Neptune, but this would be a much larger and more expensive mission than the New Frontiers program provides for. Given the great distances to the two outer planets, it will be some time before the ice giants get their first orbiters even if talks about such missions have begun.

The solar system is full of more wonders than anyone could have guessed 10 years ago, with liquid water possible as far out as Pluto, geologic activity on practically every large object, and microbial life potentially as close as the Jupiter system, or even Mars. Here's to many more spacecraft, and many more discoveries that transform our understanding of the small celestial neighborhood we float in.